Just because there are smiths who use anvils with two horns, and that there are smiths who use anvils with no horns, doesn't mean that there couldn't be a tradition among the smiths who use anvils with one horn.
The 'tradition' (if there was one) would be based on the work habits of those *having* horns on their anvils. If you have two horns (or none) the question would be moot.
Bob